THEBA CARTUSIANA. 97 
The long list of synonyms given above on the authority of responsible 
writers does not exhaust the list, the names H/. gregaria, H. pellucidula, 
AA. claustralis, and H. lucernalis, all of Ziegler, the H. ‘nnoxia and leptom- 
phala Locard and many others may be added, all indicating some slight 
local modification in the shell. 
Diagnosis.— Theba cartusiana is most closely related to 7. cantiana, 
but differs in the shell being of smaller size and more opaque when aged ; 
the spire is more depressed, the apertural rib more developed, and the 
umbilicus much smaller and more contracted. 
INTERNALLY, it differs by the much less degenerate stage of the dart-sac 
and its accessory gland, which in the present species retain the general 
outward aspect of those organs, while in 7’. cantiana they have dwindled 
into a long and slender ccecum. 
Description.—The ANIMAL has a somewhat slender BODY, obtuse in front, 
narrowly acuminate and somewhat keeled behind, of a yellowish-grey colour, be- 
coming yellower dorsally, but more translucent and colourless in the rear; the 
whole upper surface is overspread by somewhat small irregularly-shaped and 
slightly darker tubercles, many speckled with opaque-white at their summits, 
which become elongate and sinuate in shape when the animal is fully extended ; 
the DORSAL GROOVES are indistinct and enclose a longitudinal row of narrow and 
almost linear tubercles; the remainder of the tubereculation on the anterior end 
of the body is directed obliquely forward and downward. GENITAL GROOVES 
almost imperceptible, especially on the left side; FACIAL AREA simply tubercular ; 
FOOT-MARGIN or fringe narrow with fine blackish-grey lineolation; FOOT-SOLE 
yellowish-grey, narrowly margined by a darker grey; OMMATOPHORES long and 
slender, when fully extended finely tuberculate, and showing the dark retractors 
along the whole length of their upper surface, and continuing for a space along 
each side of the dorsum; LOWER TENTACLES unusually long, with their dark 
retractors well marked and deeply pigmented at their apices, and at their bases 
a muscular divarication is perceptible through the skin ; MANTLE variable in pig- 
mentation, but usually yellowish, marbled and flecked with black, the margin 
brown or brownish ; with the RESPIRATORY ORIFICE darkly and broadly defined, 
especially above. The EPIPHRAGM is usually thick, solid, and of a dull opaque, 
cretaceous white. 
The shell when containing the animal is on the upper side of a general pale 
leaden colour, with a brownish tinge on the uppermost whorls; the basal region is 
usually whitish, tinged faintly with brownish ; the peripheral region shows very 
perceptibly the very elongate, pale yellowish RENAL-ORGAN at the commencement 
of the penultimate whorl, the upper margin of the organ being almost coincident 
with the point of junction of the upper lip of the aperture with the shell; the vena- 
tion of the organ 1s quite visible through the shell, as are also the main ramifications 
of the pulmonary vessels on the body whorl near the aperture. 
Fic. 141. Fic. 142. Fic. 143. Fic. 144. 
Fic. 141.—Frontal aspect, natural size; and Fic. 142.—Upper aspect of 7heba carthusianella, 
enlarged (after Draparnaud). 
Fic. 143.—Frontal aspect; and Fic. 144.—Upper aspect of 7heba carthusiana, natural size 
(after Dupuy). 
SHELL globosely depressed, spire only slightly raised, but more convex basally ; 
WHORLS 6, rounded but with a slight supra-peripheral angulation ; of an opaque 
and somewhat opalescent milky-white colour, becoming brownish and more trans- 
lucent as the aperture is approached, where this colouration is abruptly interrupted 
by the broad whitish cincture, representing the well-developed and whitish internal 
submarginal RIB, as seen through the shell substance, the outer apertural margin 
is brown ; the shell surface is smooth and glossy, with a few subobsolete striz, and 
also overspread with irregularly reticulate microscopic sculpture, and faint spiral 
3/9/17 G 
